• Angiología 11/2010; 62(6):237-239.
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    ABSTRACT: BACKGROUND: Stickler syndrome is a connective tissue disorder characterized by ocular, skeletal, orofacial and auditory defects. It is caused by mutations in different collagen genes, namely COL2A1, COL11A1 and COL11A2 (autosomal dominant inheritance), and COL9A1 and COL9A2 (autosomal recessive inheritance). The auditory phenotype in Stickler syndrome is inconsistently reported. Therefore we performed a systematic review of the literature to give an up-to-date overview of hearing loss in Stickler syndrome, and correlated it with the genotype. METHODS: English-language literature was reviewed through searches of PubMed and Web of Science, in order to find relevant articles describing auditory features in Stickler patients, along with genotype. Prevalences of hearing loss are calculated and correlated with the different affected genes and type of mutation. RESULTS: 313 patients (102 families) individually described in 46 articles were included. Hearing loss was found in 62.9%, mostly mild to moderate when reported. Hearing impairment was predominantly sensorineural (67.8%). Conductive (14.1%) and mixed (18.1%) hearing loss was primarily found in young patients or patients with a palatal defect. Overall, mutations in COL11A1 (82.5%) and COL11A2 (94.1%) seem to be more frequently associated with hearing impairment than mutations in COL2A1 (52.2%). CONCLUSIONS: Hearing impairment in patients with Stickler syndrome is common. Sensorineural hearing loss predominates, but also conductive hearing loss, especially in children and patients with a palatal defect, may occur. The distinct disease-causing collagen genes are associated with a different prevalence of hearing impairment, but still large phenotypic variation exists. Regular auditory follow-up is strongly advised, particularly because many Stickler patients are visually impaired.
    Orphanet Journal of Rare Diseases 10/2012; 7(1):84. · 3.96 Impact Factor
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    ABSTRACT: Collagen is the most abundant protein in the human body. Collagen forms a major part of connective tissue, which can be described as the supportive tissue of the organs of the body. Defect in collagen causes various syndromes, including stickler syndrome. Here, stickler syndrome associated 11 human collagen proteins retrieved from National Center for Biotechnology Information (NCBI) Entrez protein database are characterized by using proteomics tools and online proteomics servers to give a detailed description of stickler syndrome-causing human collagen proteins. Primary structure analysis shows that all the 11 stickler syndrome-causing collagen proteins are rich in glycine (23-28%) and proline (16-18%) residues. The computed pI value indicates that the collagen proteins, NP_542197.1, NP_542196.1, NP_001845.2, NP_542411.1, AAF04726.1, AAF04725.1 and AAF04724.1, are acidic, (pI 7), and the protein, NP_001835.2 is neutral (pI =~ 7) in character. The very low Aliphatic Index (AI) (38-50) infers that the collagen proteins may become unstable at high temperature. Based on the Instability Index, the Expasy’s ProtParam classifies the collagen proteins as stable. Secondary structure analysis shows that all the 11 collagen proteins are found to be of predominant coil structure content (100%), and the Secondary Structure Content Prediction server (SSCP) classifies as irregular secondary structure class. The irregular structure of collagen proteins is due to the rich content of more flexible glycine and hydrophobic proline amino acids. SOSUI server predicts one transmembrane region (IRLGAPQSLVLLTLLVAAVLRCQ) in alpha 1 type II collagen proteins. The predicted transmembrane region is visualized and analyzed using helical wheel plot generated by EMBOSS pepwheel tool and it is found that the helical wheel consists of hydrophobic residues. The hydrophobicity of predicted transmembrane region is also well-documented by the Kyte and Doolittle mean hydrophobicity profile.

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Jun 4, 2014